Reduced wire count high speed data cable

ABSTRACT

A high speed video cable carries signals according to the High-Definition Multimedia Interface (HDMI) or DisplayPort standards, and includes a raw cable and a boost device. The raw cable is exclusively constructed with either Shielded Twisted Pairs (STP) or coaxial lines which to carry all signals on either shielded wires or their shields. The high speed signals are carried on the shielded wires to the boost device where any common mode noise induced by the signals on the shields is removed. Some auxiliary signals including power are carried on ungrounded shields. This achieves a reduction in the number of wires in the cable leading to a thinner, lighter, and less costly HDMI or DisplayPort Cable. The use of a uniform technology, either STP or coax, also permits simpler and lower cost production and assembly of the cable.

FIELD OF THE INVENTION

The present invention relates to the construction of boosted high speeddata cables, which carry high speed signal lines.

BACKGROUND OF THE INVENTION

The distribution of television signals has increasingly become based ondigital methods and digitally encoded forms of video and audio signals.At the same time, higher resolution (high definition TV) has becomeavailable in the market place, commensurate with larger and higherdefinition displays. To meet the requirement of interconnecting suchhigh definition displays with digital signal sources such as DigitalVersatile Disc (DVD) players and receivers/decoders for digitalsatellite and digital cable distribution of video material, a digitalinterface standard has evolved, known as the High-Definition MultimediaInterface (HDMI). A detailed specification for HDMI can be obtained fromthe “hdmi.org” website. The HDMI specification currently available andused in this application is HDMI specification version 1.4a dated Mar.4, 2010, which is incorporated herein by reference.

HDMI cables of various construction may be used for transmitting highspeed digital signals from digital signal sources, including, but notlimited to, the examples listed above, to digital displays or otherequipment designed to receive signals according to the HDMIspecification.

A HDMI cable carries not only four high speed differential signals whichare shielded, but also a number of lower speed signals, power andground, the whole being further shielded by an outer braid. Theresulting complex cable configuration with numerous wires, some of whichare individually shielded, is expensive to manufacture and terminate.

Another standard for connecting video source to a video sink, ispublished as the DisplayPort standard by the Video Electronics StandardsAssociation (VESA). The latest DisplayPort specification used in thisapplication is DisplayPort v1.2, dated Jan. 5, 2010, a copy of which maybe obtained from www.vesa.org. The DisplayPort standard specifies a highspeed data cable that is intended primarily to be used between acomputer and its display monitor or a home-theater system. A cablemeeting the DisplayPort standard is very similar to an HDMI cable, themain difference being in the respective physical connectors.

Therefore there is a need in the industry for developing an improved andeasier to manufacture high speed cable, which would avoid or mitigatethe shortcomings of the prior art and provides significant economies atthe same time.

SUMMARY OF THE INVENTION

Therefore there is an object of the invention to provide an improvedhigh speed cable with reduced wire count, which would have superiorproperties over existing prior art cables.

According to one aspect of the invention, there is provided a digitalvideo cable for carrying one or more high speed differential digitaldata signals and one or more auxiliary signals between a video sourcedevice and a video sink device according to a cable specification, thecable comprising: a boost device; a raw cable having one or more dualshielded cable elements, each dual shielded cable element comprising twoshielded conductors and a shield; the shielded conductors of at leastone dual shielded cable element extending between the video sourcedevice and the boost device; the shields of said one or more dualshielded cable elements extending between the video source device andthe video sink device; wherein the shield of the at least one dualshielded cable element is adapted to carry an auxiliary signal; andwherein the shielded conductors of said at least one dual shielded cableelement are adapted to carry a high speed differential digital datasignal.

In the cable described above, said one or more dual shielded cableelements are dual coaxial elements, each comprising two coaxial lineswhose shields are joined, and each coaxial line enclosing one shieldedconductor. Alternatively, only some of said one or more dual shieldedcable elements may bedual coaxial elements, each comprising two coaxiallines whose shields are joined, and each coaxial line enclosing oneshielded conductor.

In a modification to the cable design, the raw cable may further includea coaxial line having a shield enclosing one shielded conductor, thecoaxial line extending between the video source device and the videosink device; the shield is adapted to carry another auxiliary signal,and the shielded conductor is adapted to carry yet another auxiliarysignal.

Alternatively, in the cable described above, said one or more dualshielded cable elements are Shielded Twisted Pairs (STP), eachcomprising a shield enclosing the two shielded conductors. Yetalternatively, only some of said one or more dual shielded cableelements may be Shielded Twisted Pairs (STP), each comprising a shieldenclosing the two shielded conductors.

Yet alternatively, the raw cable comprises said one or more dualshielded cable elements only, i.e. excluding any other wires between thevideo source device and the video sink device, each dual shieldedelement comprising one of the following:

-   -   (i) a dual coaxial element, comprising two coaxial lines whose        shields are joined, each coaxial line enclosing one shielded        conductor; or    -   (ii) a Shielded Twisted Pair (STP), comprising a shield        enclosing the two shielded conductors.

In one embodiment of the invention, the cable specification is theHigh-Definition Multimedia Interface (HDMI) standard. In anotherembodiment of the invention, the cable specification is the DisplayPortstandard.

The cable further comprises a first circuit carrier for connecting thevideo source device to the raw cable, wherein the first circuit carrierfurther comprises terminals for connecting the high speed differentialdigital data signal from the video source device to the shieldedconductors of said at least one dual shielded cable element. The firstcircuit carrier further comprises terminals for connecting at least oneauxiliary signal from the video source device to the shield of said atleast one dual shielded cable element.

The cable may also comprise a second circuit carrier for connecting theraw cable to the video sink device, wherein the second circuit carriercomprises the boost device.

The cable of the embodiment of the invention according to the HDMIspecification is suitable for transmitting high speed differentialdigital data signals, which are Transition Minimized DifferentialSignaling (TMDS) signals; and auxiliary signals, which are ConsumerElectronics Control (CEC), Serial Clock (SCL), Hot Plug Detect (HPD),and +5V Power signals.

The HDMI cable of the embodiments of the invention comprises: theshielded conductors of four dual shielded cable elements are extendedbetween the video source device and the boost device; the shieldedconductors of the four dual shielded cable elements are adapted to carryrespective four high speed differential digital data signals, which areTransition Minimized Differential Signaling (TMDS) signals; the shieldedconductors of one other dual shielded cable element, extending betweenthe video source device and the video sink device, are adapted to carryan auxiliary signal, which is a HDMI Ethernet and Audio Return Channel(HEAC) differential signal; and the shields of the four dual shieldedcable elements and said one other dual shielded cable element areadapted to carry auxiliary signals, which are Consumer ElectronicsControl (CEC), Serial Clock (SCL), Serial Data (SDA), Digital DataChannel (DDC)/CEC Ground, and +5V Power signals.

In the HDMI cable, the boost device may also comprises an equalizer andan amplifier for equalizing and boosting the TMDS signals respectively.

The cable of the embodiment of the invention according to theDisplayPort specification has been designed as follows: the shieldedconductors of four dual shielded cable elements are extended between thevideo source device and the boost device; the shielded conductors of thefour dual shielded cable elements are adapted to carry respective fourhigh speed differential digital data signals, which are Main Line lanes;the shielded conductors of one other dual shielded cable element,extending between the video source device and the video sink device, areadapted to carry an auxiliary signal, which is an Auxiliary Channel (AUXCH) differential signal; and the shields of the four dual shielded cableelements and said one other dual shielded cable element are adapted tocarry auxiliary signals, which are CONFIG1, CONFIG2, Ground, Hot PlugDetect (HPD), and DisplayPort power (DP_PWR) signals.

The Display Port cable of the embodiments of the present invention, theboost device may also comprise an equalizer and an amplifier forequalizing and boosting the Main Line lanes respectively.

In the cable described above, an impedance of said at least one dualshielded cable element may be lower than a nominal impedance of thecable specified in the cable specification. In this case, the cablefurther comprises: a first circuit carrier connecting the video sourcedevice to the raw cable, the first circuit carrier including two paddingresistors, each padding resistor being in series with a respectiveshielded conductor of said at least one dual shielded cable element; anda second circuit carrier connecting the raw cable to the video sinkdevice, the boost device being mounted on the second circuit carrier forterminating said at least one dual shielded cable element, and forboosting the high speed differential digital data signal.

According to another aspect of the invention, there is provided a methodfor transmitting one or more high speed differential digital datasignals and a one or more auxiliary signals from a video source deviceto a video sink device over a digital video cable having a raw cable anda boost device, the method comprising: carrying at least one high speeddifferential digital data signal from the video sink device to a boostdevice in a pair of shielded conductors of the raw cable; boosting theat least one high speed differential digital data signal in the boostdevice to produce a boosted signal, and transmitting the boosted signalto the video sink device; and carrying at least one auxiliary signal ona shield of the pair of the shielded conductors.

The method further includes equalizing the at least one high speeddifferential digital data signal in the boost device.

In the method described above, the transmitting comprises transmittingover the digital video cable, which is one of the following: aHigh-Definition Multimedia Interface (HDMI) cable; a DisplayPort cable.In the embodiments of the invention, the cable specification may be theHigh-Definition Multimedia Interface (HDMI) standard, or alternatively,it may be the DisplayPort standard.

Thus, an improved reduced wire count high speed data cable and a methodof transmitting digital signals over the cable have been provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example,with reference to the accompanying drawings in which:

FIG. 1A shows a simplified boosted cable 10 to illustrate the principleof transmitting a single-ended signal and a differential signal over ashielded cable comprising a dual shielded cable element 12, which is aShielded Twisted Pair (STP), and a boost circuit 20;

FIG. 1B shows a dual coaxial element 12B that may be used instead of thedual shielded cable element 12 of FIG. 1A;

FIG. 2 shows a configuration 100 of a generic Boosted Digital VideoCable 102.j which may be of any one “j” of a number of types accordingto embodiments of the invention, interconnecting a Video Source Device(Tx) 104 and a Video Sink Device (Rx) 106;

FIG. 3 shows a Basic Coax HDMI Cable 102.1 based on coax technologyaccording to a first embodiment of the invention;

FIG. 4 shows a Basic STP HDMI Cable 102.2 based on Shielded Twisted Pair(STP) technology according to a second embodiment of the invention;

FIG. 5 shows a HEAC-Capable Coax HDMI Cable 102.3 based on coaxtechnology according to a third embodiment of the invention;

FIG. 6 shows a HEAC-Capable STP HDMI Cable 102.4 based on ShieldedTwisted Pair (STP) technology according to a fourth embodiment of theinvention;

FIG. 7 shows a Coax DisplayPort Cable 102.5 based on coax technologyaccording to a fifth embodiment of the invention;

FIG. 8 shows a STP DisplayPort Cable 102.6 based on Shielded TwistedPair (STP) technology according to a sixth embodiment of the invention;

FIG. 9 shows a three coax line cross sections, to illustrate acomparison between exemplary design choices, including a standard coax902; a reduced-outer-diameter coax 904; and an increased-core-diametercoax 906; and

FIG. 10 shows a Low-Impedance (Low Z0) Coax HDMI Cable 102.10 which isidentical to the Basic Coax HDMI Cable 102.1 of FIG. 1 except for aLow-Impedance Input Paddle Board 114.10 which replaces the first InputPaddle Board 114.1.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Embodiments of the present invention describe a boosted high speed cablecomprising shielded high speed signal lines and carrying other signalsof lower speed as well as power and ground, in which the shields of theshielded high speed signal lines are used in carrying the lower speedsignals and power and ground.

The inherent characteristics and manufacturing imperfections ofhigh-speed differential signaling cables such as may be used to carryHDMI signals have an adverse effect on the high-speed signals carried bythe cable. To mitigate these effects, various boosted high speed datacables have been proposed by the industry. For example, in thepreviously filed US application of the same assignee, Ser. No.11/826,713 filed on Jul. 18, 2007, a boost device is embedded in thecable, the contents of the patent application being incorporated hereinby reference.

The inventors have discovered that the boost device may not only be usedto equalize and boost the signal, as described in the U.S. applicationSer. No. 11/826,713 cited above, but may also be used to advantage inother ways, specifically to allow the individual shields of thedifferential high speed signals to be used for carrying other signals.

In a cable of the prior art, the shields are all tied to ground in aneffort to reduce electro-magnetic interference (EMI). In a cableaccording to any of the embodiments of the invention, EMI shielding isstill provided, but instead of tying the shields of the high-speed HDMIsignals to ground, the lower speed signals as well as power and ground,are sent over the shields.

FIG. 1A shows a simplified boosted cable 10 to illustrate the principleof transmitting a single-ended signal and a differential signal over ashielded cable. The simplified boosted cable 10 comprises a dualshielded cable element 12 which is a Shielded Twisted Pair (STP)including a single shield 14 enclosing first and second signal wires(two shielded conductors) 16 and 18 respectively, and a boost circuit 20having inputs i+ and i− and outputs o+ and o−. The inputs i+ and i− ofthe boost circuit 20 are a differential input pair and the outputs o+and o− of the boost circuit 20 are a differential output pair.

The simplified boosted cable 10 receives a single-ended signal “A” and adifferential signal “D” comprising polarities D+i and D−i at the inputof the simplified boosted cable 10, and is designed to deliver thesesignals substantially undistorted at its output. The boost circuit 20includes an equalizer circuit (EQ) and a differential amplifier (Amp)for equalizing and boosting the differential signal “D”.

The signal wires 16 and 18 carry the differential signal “D”, comprisingpolarities D+i and D−i respectively from the input of the simplifiedboosted cable 10 through the dual shielded cable element 12 to theinputs i+ and i− of the boost circuit 20. The outputs o+ and o− of theboost circuit 20 deliver a processed differential signal comprisingpolarities D+o and D−o to the output of the simplified boosted cable 10,which represent the differential signal “D”.

The single shield 14 carries a single-ended signal “A” directly from theinput of the simplified boosted cable 10 to its output.

The processing functions of the boost circuit 20 include: receiving thedifferential input signal; removing any common mode component of thedifferential input signal; equalizing the signal to compensate forsignal impairments introduced by the dual shielded cable element 12; andoutputting a boosted version of the equalized differential signal “D”.

To summarize, the differential signal is a high-speed data signal “D”,which may benefit from equalization and boosting while the single-endedsignal “A” may be a ground signal, a power supply signal, or any lowspeed signal which does not require equalization or boosting.

Along the length of the STP raw cable 12, a small fraction of thesingle-ended signal “A” is unavoidably coupled as undesirable noisethrough distributed capacitances 22 and 24 into the signal wires 16 and18 respectively, thus affecting the differential signal “D”. Given that,by the construction of the dual shielded cable element 12, thecapacitances 22 and 24 are essentially equal, the polarities D+i and D−irespectively are equally affected, and the coupled noise manifestsitself as common mode noise.

At the receiving end of the dual shielded cable element 12, the boostcircuit 20 receiving the differential signal “D”, provides sufficientcommon-mode rejection such that the common mode noise is not convertedinto a differential signal. The ouputs o+ and o− of the boost circuit20, that produces a boosted signal, is then a clean differential signalwhich is delivered at the output of the simplified boosted cable 10.

Alternatively, as shown in FIG. 1B, a dual coaxial element 12B may beused instead of the dual shielded cable element 12. The dual coaxialelement 12B is comprised of two coaxial lines 26 and 28 forming a coaxpair 30 whose outer conductors (shields) are joined together, the joinedshields providing the connection for the single-ended signal “A”. Thecoaxial line 26 carries the polarity D+i of the differential signal “D”on its inner conductor 32, while the coaxial line 28 carries thepolarity D−i of the differential signal “D” on its inner conductor 34.Coupling between the single-ended signal “A” and the inner conductors 32and 34 which are also referred to as shielded conductors, throughdistributed capacitances 36 and 38 respectively is analogous to the caseof the dual shielded cable element 12, resulting in common mode noiseonly which is rejected by the boost circuit 20.

In the following figures, various boosted HDMI cable configurations areshown which are embodiments of the invention that are based on the cableelements described in FIGS. 1A and 1B.

FIG. 2 shows a configuration 100 of a generic Boosted Digital VideoCable 102.j which may be of any of a number of types to be describedbelow, connecting a Video Source Device (Tx) 104 to a Video Sink Device(Rx) 106. The Boosted Digital Video Cable 102.j comprises a Raw Cable108.j, and Input and Output Connectors 110 and 112 respectively.

The Input Connector 110 connects the Raw Cable 108.j to the Video SourceDevice (Tx) 104, and comprises an Input Paddle Board 114.j for providingconnectivity between signals from the Video Source Device (Tx) 104 andfacilities (wires, shields) of the Raw Cable 108.j.

The Raw Cable 108.j includes dual shielded cable elements and optionallya single coaxial line, for carrying the video signals which are highspeed differential data signals as well as auxiliary signals as definedby cable specifications. Alternatively, the raw cable may include dualshielded cable elements only, i.e. excluding any other wires between thevideo source device and the video sink device.

Various embodiments of the Raw Cable 108.j are described below, coveringHDMI and DisplayPort specifications and using either coaxial or shieldedtwisted pair (STP) technology.

The Output Connector 112 connects the Raw Cable 108 to the Video SinkDevice (Rx) 106, and comprises an Output Paddle Board 116.j including aCable Boost Device 118, for providing connectivity between thefacilities (wires, shields) of the Raw Cable 108.j and the Video SinkDevice (Rx) 106. The Cable Boost Device 118 is connected between some ofthe wires of the cable and the input of the Video Sink Device (Rx) 106.The Cable Boost Device 118 includes a number of Boost Circuits 20, oneBoost Circuit 20 for terminating the dual shielded cable elements of theRaw Cable 108 which carry the high speed differential digital datasignals that arrive from the Video Source Device (Tx) 104 over the RawCable 108.

The Input Paddle Board 114.j and the Output Paddle Board 116.jconstitute first and second circuit carriers which are convenientlyconstructed as small printed circuit boards (PCB) and may be configuredto provide the mechanical support for connector contacts according tothe cable specification, for example according to the HDMI orDisplayPort standards.

FIG. 3 shows a Basic Coax HDMI Cable 102.1 based on coax technology,including a circuit carrier in the form of a first Input Paddle Board114.1, a first Raw Cable 108.1, and a first Output Paddle Board 116.1according to an embodiment of the invention. The first Raw Cable 108.1includes a total of nine individual coaxial lines arranged as four dualshielded cable elements, that is coax pairs 202, 204, 206 and 208, and asingle coaxial line 210. Each coax pair 202 to 208 comprises two coaxiallines with inner signal wires labeled as “a” and “b”, and two shieldswhich are joined together such that the joined shields form a singleconductive path. Thus, each of the coax pairs 202 to 208 provides threeelectrical connections, i.e. one differential connection (wires “a” and“b”) and one single-ended connection (the joined shields), as describedearlier (see FIG. 1B). The single coaxial line 210 provides only twoconductive paths, the inner signal wire “a” and the shield.

The Cable Boost Device 118 is comprised within the first Output PaddleBoard 116.1, and has high speed differential signal inputs D2(polarities D2+, D2−), D1 (D1+, D−), D0 (D0+, D0−), a D3 (D3+, D3−) andcorresponding boosted outputs C2 (polarities C2+, C2−), C1 (C1+, C1−),C0 (C0+, C0−), and C3 (C3+, C3−). In addition, the Cable Boost Device118 has ground and power inputs (GND, +5V), and a programming input(Pgm). The programming input is used to program parameters of the CableBoost Device 118 in manufacturing. In normal operation this input is notactive, and is effectively grounded (connected to GND) through a lowresistance within the Cable Boost Device 118.

HDMI signals may be classified as either high speed differential datasignals or auxiliary signals. The high speed differential data signalsinclude Transition Minimized Differential Signaling (TMDS) Data 0, TMDSData 1, TMDS Data 2, and TMDS Clock. The auxiliary signals are thefollowing single ended signals: Consumer Electronics Control (CEC),Serial Clock (SCL), Serial Data (SDA), Utility, and Hot Plug Detect(HPD). A +5V Power and a Digital Data Channel (DDC)/CEC Groundconnection is also provided through the cable. The +5V Power and theDDC/CEC Ground connections are included in the auxiliary signals forsimplicity here.

The signals from the Video Source Device (Tx) 104 are connected toterminals in an Input Connection Field 212 of the Basic Coax HDMI Cable102.1, and recovered at the opposite end of the cable with terminals ofan Output Connection Field 214 for transmission to the Video Sink Device(Rx) 106. Standard HDMI signal names and corresponding terminal labelsof the Input and Output Connection Fields 212 and 214 are listed inTable 1, which shows the preferred connection arrangement, or signalallocation scheme, for the Basic Coax HDMI Cable 102.1.

Referring to FIG. 3 and Table 1, each of the four HDMI high speeddifferential data signals, TMDS Data 0, TMDS Data 1, TMDS Data 2, andTMDS Clock, are routed through the Basic Coax HDMI Cable 102.1 asdescribed in the following:

The TMDS Data 2 differential signal, comprising TMDS Data2+ and TMDSData2− is:

-   -   connected from the Video Source Device (Tx) 104 to txD2+ and        txD2− terminals in the Input Connection Field 212;    -   routed in the first Input Paddle Board 114.1 to the input of the        raw cable, namely the inner signal wires “a” and “b” of the coax        pair 202;    -   routed through the inner signal wires “a” and “b” of the coax        pair 202 of the first Raw Cable 108.1;    -   coupled from the end of the first Raw Cable 108.1 to D2+ and D2−        inputs of the Cable Boost Device 118 in the first Output Paddle        Board 116.1; and    -   coupled from the C2+ and C2− outputs of the Cable Boost Device        118 to rxD2+ and rxD2− terminals in the Output Connection Field        214.

The other three HDMI high speed differential data signals (TMDS Data 0,TMDS Data 1, and TMDS Clock) are similarly connected, see Table 1.

The shields of the HDMI high speed data signals (TMDS Data0 Shield, TMDSData1 Shield, TMDS Data2 Shield, and TMDS Clock Shield), as well as theDDC/CEC Ground signal from the Video Source Device (Tx) 104 areconnected to terminals txD0 s, txD1 s, txD2 s, txCKs, and txGnd of theInput Connection Field 212, and tied to an input common ground node 216in the first Input Paddle Board 114.1 whence the input common groundnode 216 is connected to the shield of the single coaxial line 210.

In the first Output Paddle Board 116.1, the shield of the single coaxialline 210 is connected to an output common ground node 218 which isfurther connected to the ground (GND) input of the Cable Boost Device118, and to shield and ground connections of the Video Sink Device (Rx)106, namely terminals rxD0 s, rxD1 s, rxD2 s, and rxGnd. The TMDS ClockShield of the Video Sink Device (Rx) 106 is connected through a terminalrxCKs to the programming (Pgm) input of the Cable Boost Device 118, andso is indirectly grounded through the small resistance within the CableBoost Device 118. This allows the Cable Boost Device 118 to beprogrammed from the HDMI connector after the boosted cable is assembledwithout requiring any additional wire to access it. Alternatively, therxCKs terminal may be grounded directly at the output common ground node218 along with the other shield connections.

The remaining auxiliary signals (CEC, SCL, SDA, Utility, +5V Power, andHPD), are connected in the first Input Paddle Board 114.1 to terminalstxCEC, txSCL, txSDA, txUt, txPWR, and txHPD respectively. In the firstOutput Paddle Board 116.1., they are connected to terminals rxCEC,rxSCL, rxSDA, rxUt, rxPWR, and rxHPD respectively. Compared to the HDMIhigh speed data signals which are boosted by the Boost Device 118, theseauxiliary HDMI signals are at a lower speed, bypass the Cable BoostDevice 118, and may be carried on the inner wires or over the shields ofthe coaxial lines as may be convenient. The “Utility” signal in thiscase is unused. However if it is necessary to include it, it may becarried on an additional inner wire or over the shield of a coaxial wireas way be convenient.

While four of the auxiliary signals CEC, SCL, +5V Power and HPD arecarried over the shields of the coax pairs 202 to 208, another auxiliarysignal (DDC/CEC Ground), to which also the shields of the TMDS signalsare tied) is carried over the shield of single coaxial line 210, and yetanother auxiliary signal (SDA), is carried over the inner signal wire“a” of the single coaxial line 210.

In the Basic Coax HDMI Cable 102.1, these remaining HDMI signals (exceptthe Utility signal) are carried over the cable as follows:

-   -   CEC from the terminal txCEC, over the combined shields of the        coax pair 202, to the terminal rxCEC;    -   SCL from the terminal txSCL, over the combined shields of the        coax pair 204, to the terminal rxSCL;    -   SDA from the terminal txSDA, over the inner wire “a” of the coax        210, to the terminal rxSDA;    -   +5V Power from the terminal txPWR, over the combined shields of        the coax pair 206, to the terminal rxPWR; and    -   Hot Plug Detect from the terminal txHPD, over the combined        shields of the coax pair 208, to the terminal rxHPD.

In the first Output Paddle Board 116.1 the +5V Power is also connectedto the power input (+5V) of the Boost Device 218.

TABLE 1 Preferred Signal Routing in Basic Coax HDMI Cable 102.1 BoostInput Boost De- Output Connec- Raw De- vice Connec- HDMI tion Cable viceOut- tion Signal Name 212 108.1 Input put 214 TMDS Data2 Shield txD2s210.shield --> --> rxD2s TMDS Data2+ txD2+ 202.a D2+ C2+ rxD2+ TMDSData2− txD2− 202.b D2− C2− rxD2− TMDS Data1 Shield txD1s 210.shield -->--> rxD1s TMDS Data1+ txD1+ 204.a D1+ C1+ rxD1+ TMDS Data1− txD1− 204.bD1− C1− rxD1− TMDS Data0 Shield txD0s 210.shield --> --> rxD0s TMDSData0+ txD0+ 206.a D0+ C0+ rxD0+ TMDS Data0− txD0− 206.b D0− C0− rxD0−TMDS Clock Shield txCKs 210.shield — — — Pgm --> rxCKs TMDS Clock+ txCK+208.a D3+ C3+ rxCK+ TMDS Clock− txCK− 208.b D3− C3− rxCK− DDC/CEC GroundtxGnd 210.shield GND --> rxGnd CEC txCEC 202.shield --> --> rxCEC SCLtxSCL 204.shield --> --> rxSCL SDA txSDA 210 --> --> rxSDA Utility txUtn/c — — rxUt +5 V Power txPWR 206.shield +5 V --> rxPWR Hot Plug DetecttxHPD 208.shield --> --> rxHPD

FIG. 4 shows a Basic STP HDMI Cable 102.2 based on Shielded Twisted Pair(STP) technology, including a second Input Paddle Board 114.2, a secondRaw Cable 108.2, and a second Output Paddle Board 116.2 according toanother embodiment of the invention.

The Input and Output Connection Fields 212 and 214, including therespective terminals remain unchanged from the Basic Coax HDMI Cable102.2. The second Raw Cable 108.2 comprises five Shielded Twisted Pairs(STPs) 302, 304, 306, 308, and 310, each comprising a shield and twosignal wires “a” and “b” as described in FIG. 1A. The allocation of thestandard HDMI signals to connections through the second Raw Cable 108.2is provided by configurations of the second Input and Output PaddleBoards 114.2 and 116.2 respectively.

The STPs 302, 304, 306, 308, and 310 of the second Raw Cable 108.2provide 15 (3×5) distinct conductive paths, compared to the 14 paths(3×4+1) of the first Raw Cable 108.1. Hence an additional path isavailable which is advantageously used in a modification of the signalassignments. This is illustrated in FIG. 4 as well as in Table 2 whichlists the preferred arrangement for the Basic STP HDMI Cable 102.2.

Because of the additional line available in the second Raw Cable 108.2,compared to the first Raw Cable 108.1, it is possible to use a shieldconnection (a common node 312 connected to the shield of the STP 308) toconnect the shields of all high speed signals (D0, D1, D2, and CK), anduse a separate shield connection (the shield of the STP 310) for theground connection.

The preferred assignments shown in Tables 1 and 2 are to some extentarbitrary, and may be adapted to best utilize the space on the paddleboards and the configurations of the respective connectors.

TABLE 2 Preferred Signal Routing in Basic STP HDMI Cable 102.2 BoostInput Boost De- Output Connec- Raw De- vice Connec- HDMI tion Cable viceOut- tion Signal Name 212 108.2 Input put 214 TMDS Data2 Shield txD2s308.shield --> --> rxD2s TMDS Data2+ txD2+ 302.a D2+ C2+ rxD2+ TMDSData2− txD2− 302.b D2− C2− rxD2− TMDS Data1 Shield txD1s 308.shield -->--> rxD1s TMDS Data1+ txD1+ 304.a D1+ C1+ rxD1+ TMDS Data1− txD1− 304.bD1− C1− rxD1− TMDS Data0 Shield txD0s 308.shield --> --> rxD0s TMDSData0+ txD0+ 306.a D0+ C0+ rxD0+ TMDS Data0− txD0− 306.b D0− C0− rxD0−TMDS Clock Shield txCKs 308.shield — — — Pgm --> rxCKs TMDS Clock+ txCK+308.a D3+ C3+ rxCK+ TMDS Clock− txCK− 308.b D3− C3− rxCK− DDC/CEC GroundtxGnd 310.shield GND --> rxGnd CEC txCEC 306.shield --> --> rxCEC SCLtxSCL 310 --> --> rxSCL SDA txSDA 310.b --> --> rxSDA Utility txUt n/c —— rxUt +5 V Power txPWR 302.shield +5 V --> rxPWR Hot Plug Detect txHPD304.shield --> --> rxHPD

In this embodiment of the invention, the raw cable includes STPs only,i.e. excluding any other wires between the video source device and thevideo sink device.

HEAC Capability

In a Supplement 2 to the HDMI specification version 1.4. dated Jun. 5,2009 cited above, a “HDMI Ethernet and Audio Return Channel” (HEAC) isspecified. The HEAC channel is carried in a HEAC-capable HDMI cable as adifferential data signal, i.e. negative and positive polarity signalsHEAC− and a HEAC+ respectively, which replace the Hot Plug Detect (HPD)signal and the previously unused “Utility” signal respectively of thestandard HDMI signal set. The HEAC channel is a passive channel whichdoes not require boosting by the Cable Boost Device 118. However, itdoes require careful control of its impedance and should therefore beenclosed in a shield, either by running each polarity in a coaxial line,or both polarities over a shielded twisted pair (STP). Accordingly, onlymodified connectivity (adding the HEAC channel, with controlledimpedance lines, replacing HPD and “Utility” signals) in the paddleboards and in the raw cable are required to convert the basicHDMI,Cables (102.1 and 102.2) to accommodate the HEAC channel.

FIG. 5 shows a HEAC−Capable Coax HDMI Cable 102.3 based on coaxtechnology, and capable of carrying an HEAC channel: including a thirdInput Paddle Board 114.3, a third Raw Cable 108.3, and a third OutputPaddle Board 116.3 according to yet another embodiment of the invention.

The signals of the HEAC-capable HDMI signal set from the Video SourceDevice (Tx) 104, are connected to a HEAC-capable Input Connection Field412 of the HEAC−Capable Coax HDMI Cable 102.3, and recovered at theopposite end of the cable with a HEAC-capable Output Connection Field414 for transmission to the Video Sink Device (Rx) 106. Themodifications of the HEAC-capable Input and Output Fields 412 and 414relate to name changes compared to the Input and Output Fields 212 and214, and reflect name changes of the terminals concerned: txUt, rxUt,txHPD, and rxHPD of the Input and Output Fields 212 and 214, becometxHEAC−, rxHEAC−, txHEAC+, and rxHEAC+ of the HEAC-capable Input andOutput Fields 412 and 414.

The third Raw Cable 108.3 comprises a total of ten individual coaxiallines arranged in four dual shielded cable elements, that is coax pairs402, 404, 406, and 408, for carrying high speed digital data signals,and another dual shielded cable element, that is a coax pair 410, forcarrying a differential auxiliary signal. Each coax pair 402 to 410includes two coaxial lines with inner signal wires labeled as “a” and“b”, and two shields which are joined together such that the joinedshields of each coax pair form a single conductive path. Thus, each ofthe coax pairs 402 to 410 provides three electrical connections, i.e.one differential connection (wires “a” and “b”) and and one single-endedconnection (the joined shields), as described earlier (see FIG. 1B).

The assignments of the HDMI signals to the available cable connectionsin the third Input Paddle Board 114.3 and the third Output Paddle Board116.3 are similar compared to the assignments used in the first Inputand Output Paddle Boards 114.1 and 116.1 respectively. Unchangedconnections are those for the differential HDMI high-speed data channelsTMDS D2, D1, D0, and Clock, incoming from the Video Source Device 104,which are connected through the coax pairs 402, 404, 406, and 408respectively to corresponding inputs of the Cable Boost Device 118.

The differential HEAC channel is connected through the coax pair 410,and bypasses the Cable Boost Device 118. The shields of the coax pairs402, 404, 406, 408, and 410 serve as conductors for the HDMI signalsCEC, SCL, +5V Power, SDA, and DDC/CEC Ground respectively.

TABLE 3 Preferred Signal Routing in HEAC- capable Coax HDMI Cable 102.3Boost Input Boost De- Output Connec- Raw De- vice Connec- HDMI tionCable vice Out- tion Signal Name 212 108.2 Input put 214 TMDS Data2Shield txD2s 410.shield --> --> rxD2s TMDS Data2+ txD2+ 402.a D2+ C2+rxD2+ TMDS Data2− txD2− 402.b D2− C2− rxD2− TMDS Data1 Shield txD1s410.shield --> --> rxD1s TMDS Data1+ txD1+ 404.a D1+ C1+ rxD1+ TMDSData1− txD1− 404.b D1− C1− rxD1− TMDS Data0 Shield txD0s 410.shield -->--> rxD0s TMDS Data0+ txD0+ 406.a D0+ C0+ rxD0+ TMDS Data0− txD0− 406.bD0− C0− rxD0− TMDS Clock Shield txCKs 410.shield — — — Pgm --> rxCKsTMDS Clock+ txCK+ 408.a D3+ C3+ rxCK+ TMDS Clock− txCK− 408.b D3− C3−rxCK− DDC/CEC Ground txGnd 410.shield GND --> rxGnd CEC txCEC 402.shield--> --> rxCEC SCL txSCL 404.shield --> --> rxSCL SDA txSDA 408.shield--> --> rxSDA HEAC− txHEAC+ 410 --> --> rxHEAC− +5 V Power txPWR406.shield +5 V --> rxPWR HEAC+ txHEAC+ 410.b --> --> rxHEAC+

The incoming shields of the HDMI high-speed data channels TMDS D2, D1,D0, and the TMDS Clock, are tied to the DDC/CEC Ground connectionthrough the shield of the coax pair 410 of the cable, thus providing aconnection to the outgoing shields of the HDMI high-speed data channelsTMDS D2, D1, and D0. The outgoing shield of the TMDS Clock (rxCKs) isconnected to the programming pin (Pgm) of the Cable Boost Device 118 asdescribed above with reference to the Basic Coax HDMI Cable 102.1.

The preferred HDMI signal routing of the HEAC−Capable Coax HDMI Cable102.3 is listed in Table 3.

FIG. 6 shows a HEAC−Capable STP HDMI Cable 102.4, based on ShieldedTwisted Pair (STP) technology and capable of carrying an HEAC channel,including a fourth Input Paddle Board 114.4, a fourth Raw Cable 108.4,and a fourth Output Paddle Board 116.4 according to a fourth embodimentof the invention.

The HEAC-capable Input and Output Connection Fields 412 and 414 of theHEAC−Capable STP HDMI Cable 102.4, including the respective terminalsremain unchanged from the HEAC−Capable Coax HDMI Cable 102.3. The fourthRaw Cable 108.4 comprises five Shielded Twisted Pairs (STPs) 502, 504,506, 508, and 510, each comprising a shield and two signal wires “a” and“b” as described in FIG. 1A. The allocation of the HDMI signals toconnections through the fourth Raw Cable 108.4 is provided byconfigurations of the fourth Input and Output Paddle Boards 114.4 and116.4 respectively.

The STPs 502, 504, 506, 508, and 510 of the fourth Raw Cable 108.4provide 15 (3×5) distinct conductive paths, the same number as providedin the third Raw Cable 108.3. Accordingly, an analogous allocation ofthe individual signals to the Shielded Twisted Pairs including theirshields, could be made. Similarly, part of the allocation scheme couldalso be “borrowed” from the other STP based embodiment (the Basic STPHDMI Cable 102.2) and suitably modified to accommodate the HEAC signal.

A different connection allocation scheme is proposed here to illustratethe considerable latitude available in choosing configurations. Thepreferred assignments for the HEAC−Capable STP HDMI Cable 102.4 areillustrated in FIG. 6 as well as in Table 4.

As indicated earlier, the preferred assignments of signal leads in thecables are shown in the Tables 1, 2, 3, and 4. These are to some extentarbitrary. The “+5V Power” and the “DDC/CEC Ground” connections arepreferably carried on a shield; the HDMI high speed data signals (TMDSD0, D1, D2, and Clock) should always be carried on shielded conductors,i.e. the inner conductors of coax lines or the twisted signal wires ofSTPs, depending on wire type; and the lower speed connections (CEC, SCL,SDA, Utility, and HPD) may be carried on inner/ signal wires or shieldsin an arrangement that may be adapted to best utilize the space on thepaddle boards and the configuration of the respective connectors.

The use of the TMDS Clock Shield connection on the receive side (rxCKs)to access the programming pin (Pgm) of the Cable Boost Device 118 is aconvenience for programming the device in the fully assembled boostedHDMI cable. If this feature is not required, the TMDS Clock Shieldshould be grounded along with the other TDMS signal shields at both endsof the cable.

TABLE 4 Preferred Signal Routing in HEAC- capable STP HDMI Cable 102.4Boost Input Boost De- Output Connec- Raw De- vice Connec- HDMI tionCable vice Out- tion Signal Name 212 108.2 Input put 214 TMDS Data2Shield txD2s 510.shield --> --> rxD2s TMDS Data2+ txD2+ 502.a D2+ C2+rxD2+ TMDS Data2− txD2− 502.b D2− C2− rxD2− TMDS Data1 Shield txD1s510.shield --> --> rxD1s TMDS Data1 + txD1+ 504.a D1+ C1 + rxD1+ TMDSData1− txD1− 504.b D1− C1− rxD1− TMDS Data0 Shield txD0s 510.shield -->--> rxD0s TMDS Data0+ txD0+ 506.a D0+ C0+ rxD0+ TMDS Data0− txD0− 506.bD0− C0− rxD0− TMDS Clock Shield txCKs 510.shield — — — Pgm --> rxCKsTMDS Clock+ txCK+ 508.a D3+ C3+ rxCK+ TMDS Clock− txCK− 508.b D3− C3−rxCK− DDC/CEC Ground txGnd 510.shield GND --> rxGnd CEC txCEC 506.shield--> --> rxCEC SCL txSCL 508.shield --> --> rxSCL SDA txSDA 504.shield--> --> rxSDA HEAC− txHEAC--> 510 --> --> rxHEAC− +5 V Power txPWR502.shield +5 V --> rxPWR HEAC+ txHEAC+ 510.b --> --> rxHEAC+

DisplayPort Cables

FIG. 7 shows a Coax DisplayPort Cable 102.5 based on coax technology,including a fifth Input Paddle Board 114.5, a fifth Raw Cable 108.5, anda fifth Output Paddle Board 116.5 according to an embodiment of theinvention. The fifth Raw Cable 108.5 includes a total of ten individualcoaxial lines arranged in five coax pairs 602, 604, 606, 608, and 610.Each coax pair 602 to 610 comprises two coaxial lines with inner signalwires labeled as “a” and “b”, and two shields which are joined togethersuch that the joined shields form a single conductive path. Thus, eachof the coax pairs 602 to 608 provides three electrical connections, i.e.one differential connection (wires “a” and “b”) and one single-endedconnection (the joined shields), as described earlier (see FIG. 1B).

The same Cable Boost Device 118 as in the boosted HDMI cables describedabove, is comprised within the fifth Output Paddle Board 116.5.

Standard DisplayPort signals from the Video Source Device (Tx) 104, areconnected to terminals in a DisplayPort Input Connection Field 612 ofthe Coax DisplayPort Cable 102.5, and recovered at the opposite end ofthe cable at terminals of a DisplayPort Output Connection Field 614 fortransmission to the Video Sink Device (Rx) 106. The DisplayPort signalnames and corresponding terminal labels of the DisplayPort Input andOutput Connection Fields 612 and 614 are listed in Table 5, which showsthe preferred connection arrangement, or signal allocation scheme, forthe Coax DisplayPort Cable 102.5.

Referring to FIG. 7 and Table 5, each of the four DisplayPort high speeddifferential data lanes ML-L0, ML-L1, ML-L2, and ML-L3, is routedthrough the Coax DisplayPort Cable 102.5 as described in the following:

The Main Line Lane0 differential signal, comprising positive (p) andnegative (n) polarities is:

-   -   connected from the Video Source Device (Tx) 104 to txML_L0+ and        txML_L0− terminals in the DisplayPort Input Connection Field        612;    -   routed in the fifth Input Paddle Board 114.5 to the inner signal        wires “a” and “b” of the coax pair 602;    -   routed through the fifth Raw Cable 108.5 on the inner signal        wires “a” and “b” of the coax pair 602 of the fifth Raw Cable        108.5;    -   coupled from the end of the fifth Raw Cable 108.5 to D0+ and D0−        inputs of the Cable Boost Device 118 in the fifth Output Paddle        Board 116.5; and    -   coupled from the CO+ and CO− outputs of the Cable Boost Device        118 to rxML_L0+ and rxML_L0− terminals in the DisplayPort Output        Connection Field 614.

The other three main-line differential data signals (Main Line Lane1,Lane2, and Lane 3) are similarly connected, see Table 5.

All ground connections of the incoming DisplayPort connector which arelabeled txGND0, txGND1, txGND2, txGND3, txGNDaux as well as the “Return”(txGNDpwr), i.e. the power return terminal, are tied together to aninput common ground node 616 in the fifth Input Paddle Board 114.5, andconnected to the shield of the coax pair 604.

In the fifth Output Paddle Board 116.5, the shield of the coax pair 604is connected to an output common ground node 618 which is also connectedto the ground (GND) input of the Cable Boost Device 118, and to shieldand ground connections of the Video Sink Device (Rx) 106, namelyterminals rxGND0, rxGND1, rxGND2, rxGNDaux, and txGNDpwr. An exceptionis the fourth ground pin of the receive side which is connected througha terminal rxGND3 to the programming (Pgm) input of the Cable BoostDevice 118, and so is only indirectly grounded. This allows the CableBoost Device 118 to be programmed from the connector after the boostedcable is assembled without requiring any additional wire to access it.Alternatively, the rxGND3 terminal may also be grounded at the outputcommon ground node 618 along with the other ground connections.

Other DisplayPort signals CONFIG1, CONFIG2, AUX Channel (p) and (n), HotPlug, and DP_PWR, are respectively connected in the fifth Input PaddleBoard 114.5 to terminals txCONFIG1, txCONFIG2, txAuxCh+ and txAuxCh−,txHPD, and txDP_PWR. In the fifth Output Paddle Board 116.5. they arerespectively connected to terminals rxCONFIG1, rxCONFIG2, rxAuxCh+ andrxAuxCh−, rxHPD, and rxDP_PWR. Compared to the main line high speedsignals which are boosted by the Boost Device 118, these otherDisplayPort signals are at a lower speed, bypass the Cable Boost Device118, and may be carried on the inner wires or over the shields of thecoaxial lines as may be convenient. The AUX Channel signal however is ofmoderately high speed and is required to be carried in a controlledimpedance wire, for which the coax pair 610 is chosen in this embodimentof the invention.

In the Coax DisplayPort Cable 102.5, the remaining signals are carriedover the cable as follows:

-   -   CONFIG1 from the terminal txCONFIG1, over the combined shields        of the coax pair 606, to the terminal rxCONFIG1;    -   CONFIG2 from the terminal txCONFIG2, over the combined shields        of the coax pair 608, to the terminal rxCONFIG2;    -   Hot Plug from the terminal txHPD, over the combined shields of        the coax pair 610, to the terminal rxHPD; and    -   DP_PWR from the terminal txDP_PWR, over the combined shields of        the coax pair 602, to the terminal rxDP_PWR.

In the fifth Output Paddle Board 116.5 the DP_PWR is also connected tothe power input (+5V) of the Cable Boost Device 218. Even though thevoltage of DP_PWR will be lower than the HDMI +5V Power, the same CableBoost Device 218 may be designed or programmed to run at both the HDMIand the DisplayPort voltages. Alternatively, a DisplayPort specificversion of the Cable Boost Device 218 may be developed.

TABLE 5 Preferred Signal Routing in Coax DisplayPort Cable 102.5 BoostInput Boost De- Output Connec- Raw De- vice Connec- DisplayPort tionCable vice Out- tion Signal Name 212 108.1 Input put 214 Main Line Lane0txML_L0+ 602 D0+ C0+ rxML_L0+ (p) Ground (pin 2) txGND0 604.shield -->--> rxGND0 Main Line Lane0 txML_L0− 602.b D0− C0− rxML_L0− (n) Main LineLane1 txML_L1+ 604 D1+ C1+ rxML_L1+ (p) Ground (pin 5) txGND1 604.shield--> --> rxGND1 Main Line Lane1 txML_L1− 604.b D1− C1− rxML_L1− (n) MainLine Lane2 txML_L2+ 606 D2+ C2+ rxML_L2+ (p) Ground (pin 8) txGND2604.shield --> --> rxGND2 Main Line Lane2 txML_L2− 606.b D2− C2−rxML_L2− (n) Main Line Lane3 txML_L3+ 608 D3+ C3+ rxML_L3+ (p) Ground(pin 11) txGND3 604.shield Pgm --> rxGND3 Main Line Lane0 txML_L3− 608.bD3− C3− rxML_L3− (n) CONFIG1 txCONFIG1 606.shield --> --> rxCONFIG1CONFIG2 txCONFIG2 608.shield --> --> rxCONFIG2 AUX Channel (p) txAuxCh+610 --> --> rxAuxCh+ Ground (pin 16) txGNDaux 604.shield --> -->rxGNDaux AUX Channel (n) txAuxCh− 610.b --> --> rxAuxCh− Hot Plug txHPD610.shield --> --> rxHPD Return txGNDpwr 604.shield GND --> rxGNDpwrDP_PWR txDP_PWR 602.shield +5 V --> rxDP_PWR

FIG. 8 shows a STP DisplayPort Cable 102.6 based on Shielded TwistedPair (STP) technology, including a sixth Input Paddle Board 114.6, asixth Raw Cable 108.6, and a sixth Output Paddle Board 116.6 accordingto an embodiment of the invention. The sixth Raw Cable 108.6 includes atotal of five STPs 702, 704, 706, 708, and 710, each comprising a shieldand two signal wires “a” and “b” as described in FIG. 1A.

The allocation of the DisplayPort signals to connections through thesixth Raw Cable 108.6 is provided by configurations of the sixth Inputand Output Paddle Boards 114.6 and 116.6 respectively, and is analogousto the allocation in the Coax DisplayPort Cable 102.5, FIG. 7. The STPsignal assignments are illustrated in FIG. 8 which is identical to FIG.7 except for showing Shielded Twisted Pairs (STPs) 702, 704, 706, 708,and 710 instead of coax pairs 602-610. While the sixth Input and OutputPaddle Boards 114.6 and 116.6 have similar connectivity to thecorresponding fifth Input and Output Paddle Boards 114.5 and 116.5,their mechanical properties would differ in order to accommodate thedifferent termination geometries of the STPs versus the coax pairs onthe paddle boards.

All auxiliary signals, CONFIG1, CONFIG2, Hot Plug, Ground and DP_PWR,may be placed over any shields of coaxial or STP lines as may beconvenient or for an arrangement that may be adapted to best utilize thespace on the paddle boards and the configuration of the respectiveconnectors.

Low Wire Count Summary

The number of wires in a boosted high speed digital video cable such asan HDMI or DisplayPort cable, has been reduced from fourteen or more inprior art cables to nine or ten by using the shields to individuallycarry active signals as well as power and ground. This reduction isenabled by the boost device which guarantees the removal of potentiallyharmful common mode interference on the high speed data lines. Thereduction in the number of wires simplifies their alignment fortermination in the connectors. The original high speed cables use a mixof coaxial lines or shielded twisted pairs and standard wires. Theinvention provides a reduction in the construction cost of high speedcables by the use of only a single type of wire, either coaxial or STP,to carry all signals. This significantly simplifies cable assembly andallows a single step termination process, ultimately reducing cost.

Low Impedance Cables

In addition to the advantages obtained through the low wire counttechnique described above, a further cost advantage may be achieved byusing coaxial lines or Shielded Twisted Pairs (STP) of a lower impedancethan the nominal line impedance implied in the standards, for carryingthe high speed data signals in any of the Boosted Digital Video Cables102 described here.

FIG. 9 shows a three coax line cross sections, to illustrate acomparison between exemplary design choices, including a standard coax902; a reduced-outer-diameter coax 904; and an increased-core-diametercoax 906. The standard coax 902 comprises an outer insulating sheath902.a, a shield 902.b, an inner insulator 902.c, and a core wire (core)902.d.

The reduced-outer-diameter coax 904 comprises an outer insulating sheath904.a, a shield 904.b, an inner insulator 904.c, and a core wire (core)904.d. The increased-core-diameter coax 906 comprises an outerinsulating sheath 906.a, a shield 906.b, an inner insulator 906.c, and acore wire (core) 906.d.

The characteristic impedance Z0 of a coaxial line is determined bydimensions of the cable, more precisely, by the ratio of the diameter ofthe core wire to the inner diameter of the shield, and by the dielectricconstant of the inner isolator material.

The core 902.d of the thin standard coax 902 with a characteristicimpedance of 50 ohms is an American Wire Gauge (AWG) wire of about 78 μmdiameter, resulting in an overall diameter of the standard coax 902 ofabout 210 μm.

By allowing the coax to have a lower, “non-standard” characteristicimpedance it is possible for example, and without changing the insulatormaterial, to either reduce the outer diameter of the coax without havingto use a finer core wire, or to increase the core diameter while keepingthe outer diameter constant.

The core 904.d of the reduced-outer-diameter coax 904 is the same wiregauge as the core 902.d of the standard coax 902, but the shield 904.cis shrunk such that a characteristic impedance of 35 ohms is obtainedfor the reduced-outer-diameter coax 904. This results in an overalldiameter of the reduced-outer-diameter coax 902 of about 145 μm, asavings of about 30% compared to the standard coax 902 with 50 ohmcharacteristic impedance.

If the outer diameter is not changed, a thicker core wire may be used.The shield 906.b, hence the overall diameter of theincreased-core-diameter coax 906, corresponds to that of the standardcoax 902. However, the thickness of the core 906.d is increased suchthat a characteristic impedance of 35 ohms is obtained for theincreased-core-diameter coax 906, resulting in a wire size of AWG 40 forthe core 906.d of the increased-core-diameter coax 906. AWG 35corresponds to a wire diameter of about 143 μm, an almost 80% increasein thickness.

The inventors have considered the impact of deviating from the standard50 ohm coax for implementing the HDMI and DisplayPort cables describedabove, that is the Basic Coax HDMI Cable 102.1, the HEAC−Capable CoaxHDMI Cable 102.3, and the Coax DisplayPort Cable 102.5, as well as otherboosted digital video cables. To recapitulate, the Video Source Device104 transmits high speed differential signals through coax pairs to theCable Boost Device 118 which equalizes and boosts the signals beforetransmitting them to the Video Sink Device 106.

The Video Source Device 104 is designed to transmit these high speeddifferential signals over cables presenting a characteristic impedanceof 100 ohms differentially, that is 2 times 50 ohms in the case of dualcoaxial lines (coax pairs). An input circuit in the Video Sink Device106 similarly presents matching 100 ohms differential terminations tothe cable.

In the case of the boosted cables with a reduced impedance coax, theCable Boost Device 118 provides a proper output circuit for transmissionof the boosted signals to the Video Sink Device 106. An inputtermination in the Cable Boost Device 118 can be tuned to terminate areduced impedance cable with the correct impedance, for example 35 ohms,or 70 ohms differentially.

The Video Source Device 104 is designed as a current source and would beable to directly transmit into any cable impedance; no undesired signalreflections would result as long as the cable is correctly terminated atthe receiving end, that is at the Cable Boost Device 118. However,compliance testing of HDMI and DisplayPort cables requires the cable topresent a nominal 100 ohm differential impedance at source end for aunidirectional active cable and both ends for a passive cable.

FIG. 10 shows a Low-Impedance (Low Z0) Coax HDMI Cable 102.10 which isidentical to the Basic Coax HDMI Cable 102.1 of FIG. 3 except for aLow-Impedance Input Paddle Board 114.10 which replaces the first InputPaddle Board 114.1. The Low-Impedance Input Paddle Board 114.10 has thesame connectivity as the first Input Paddle Board 114.1, except foreight padding resistors R1 to R8 which are inserted between the highspeed signal terminals txD2+, txD2−, txD1+, txD1−, txD0+, txD02−, txCK+,and txCK− of the Input Connection Field 212, and the inner signal wires“a” and “b” of the corresponding coax pairs 202 to 208 of the first RawCable 108.1.

One pair of padding resistors is required to be inserted in series witheach of the inner signal wires “a” and “b” of the TMDS signals. Theresistance of each padding resistor is derived such that the combinedresistance of two padding resistors in series with the inner signalwires (the shielded conductors) of each coax pair (dual shielded cableelement) 202 to 208 is equal to the difference between the specifiednominal cable impedance and the impedance of the coax pair, for examplea 100 ohm nominal impedance is achieved by using two coax lines of 35ohm impedance, each with 15 ohm padding resistors, as a coax pair.

The padding resistors R1-R8 could be omitted without loss offunctionality, but they are provided in order to meet the specifieddifferential input impedance of 100 ohms for the Low-Impedance Coax HDMICable 102.10.

If the coax pairs 202 to 208 of the first Raw Cable 108.1 are made oflow-impedance coaxial lines, such as the reduced-outer-diameter coax 904or the increased-core-diameter coax 906 which each have an exemplarycharacteristic impedance of 35 ohms, the values of each of the paddingresistors R1 to R8 should be 50−35=15 ohms, such that each coax pair,combined with the padding resistors, presents a 2×50=100 ohm impedanceto the differential terminals of the Input Connection Field 212. Ingeneral, the resistance of each padding resistor R1 to R8 should be Xohms, where X is equal to the difference between one half of thespecified nominal impedance (e.g. 100 Ohms for HDMI) and the actualcharacteristic impedance of the coax.

Similarly, other coax based high speed video cables such as theHEAC−Capable Coax HDMI Cable 102.3 (FIG. 5) and the Coax DisplayPortCable 102.5 (FIG. 7) are easily modified by the addition of the paddingresistors R1 to R8 on their respective input paddle boards, toaccommodate low-impedance coax cables.

It is worth noting that signals other than the high speed differentialdata signals, for example the HEAC channel of HDMI and the AUX channelof DisplayPort, are not boosted by the Cable Boost Device 118. The coaxpairs transporting these signals (coax pair 410 for HEAC, and coax pair610 for the AUX channel) can not be of the low-impedance type, but mustbe regular 50 ohm coaxes.

The same techniques for using reduced impedance coax cables also appliesfor boosted HDMI and DisplayPort cables that use Shielded Twisted Pairs(STP) for transmitting the high speed differential data signals. Thecharacteristic impedance of STPs is determined by the ratio of theinsulated wire diameter to the diameter of the bare wire, and thedielectric properties of the insulation material.

Low-impedance STPs are easily made by reducing the thickness of theinsulation compared to the diameter of the bare wire. This of coursealso affects the size of the shield. A reduction in the thickness of STPwire insulation by about 30% without changing the bare wire thicknesswill reduce the (differential) impedance of the STP from a nominal 100ohms to 70 ohms. Instead of reducing the size of the STP cable in thisway, it is also possible to maintain the original overall size andincrease the bare wire thickness.

When a low impedance STP is employed in any of the boosted video cablesbased on STP technology, such as the Basic STP HDMI Cable 102.2 (FIG.4), the HEAC−Capable STP HDMI Cable 102.4 (FIG. 6), and the STPDisplayPort Cable 102.6, the same considerations as with the coax basedcables apply: the input circuit of the Cable Boost Device 118 should beprogrammed to match the STP impedance, and the input paddle board shouldbe modified to include padding resistors. Similar to the rule thatapplies in the coax case, the resistance of each padding resistor R1 toR8 in the STP case should be Y ohms, where Y is equal to one half of thedifference between the specified nominal impedance (e.g. 100 Ohms forHDMI) and the actual differential impedance of the STP.

The lowering of the characteristic impedance in coax or STP based cableswhich include boost devices has a number of advantages which may beexploited, either to reduce the size of the cable for material savings,improved flexibility, etc., or to increase the wire size withoutreducing the overall size of the cable for improved handling, and lowermaterial cost. Note that thicker wire may actually cost less to producethan very fine wire.

Although various exemplary embodiments of the invention have beendisclosed, it should be apparent to those skilled in the art thatvarious changes and modifications can be made which will achieve some ofthe advantages of the invention without departing from the true scope ofthe invention.

A person understanding this invention may now conceive of alternativestructures and embodiments or variations of the above all of which areintended to fall within the scope of the invention as defined in theclaims that follow.

1. A digital video cable for carrying one or more high speeddifferential digital data signals and one or more auxiliary signalsbetween a video source device and a video sink device according to acable specification, the cable comprising: a boost device; a raw cablehaving one or more dual shielded cable elements, each dual shieldedcable element comprising two shielded conductors and a shield; theshielded conductors of at least one dual shielded cable elementextending between the video source device and the boost device; theshields of said one or more dual shielded cable elements extendingbetween the video source device and the video sink device; wherein theshield of the at least one dual shielded cable element is adapted tocarry an auxiliary signal; and wherein the shielded conductors of saidat least one dual shielded cable element are adapted to carry a highspeed differential digital data signal.
 2. The cable of claim 1, whereinsaid one or more dual shielded cable elements are dual coaxial elements,each comprising two coaxial lines whose shields are joined, and eachcoaxial line enclosing one shielded conductor.
 3. The cable of claim 1,wherein some of said one or more dual shielded cable elements are dualcoaxial elements, each comprising two coaxial lines whose shields arejoined, and each coaxial line enclosing one shielded conductor.
 4. Thecable of claim 1, wherein the raw cable further includes a coaxial linehaving a shield enclosing one shielded conductor, the coaxial lineextending between the video source device and the video sink device; theshield is adapted to carry another auxiliary signal, and the shieldedconductor is adapted to carry yet another auxiliary signal.
 5. The cableof claim 1, wherein said one or more dual shielded cable elements areShielded Twisted Pairs (STP), each comprising a shield enclosing the twoshielded conductors.
 6. The cable of claim 1, wherein some of said oneor more dual shielded cable elements are Shielded Twisted Pairs (STP),each comprising a shield enclosing the two shielded conductors.
 7. Thecable of claim 1, wherein the raw cable comprises said one or more dualshielded cable elements only, each dual shielded element comprising adual coaxial element, comprising two coaxial lines whose shields arejoined, each coaxial line enclosing one shielded conductor.
 8. The cableof claim 1, wherein the raw cable comprises said one or more dualshielded cable elements only, each dual shielded element comprising aShielded Twisted Pair (STP), comprising a shield enclosing the twoshielded conductors.
 9. The cable of claim 1, wherein the cablespecification is the High-Definition Multimedia Interface (HDMI)standard.
 10. The cable of claim 1, wherein the cable specification isthe DisplayPort standard.
 11. The cable of claim 1, further comprising afirst circuit carrier for connecting the video source device to the rawcable.
 12. The cable of claim 11, wherein the first circuit carrierfurther comprises terminals for connecting the high speed differentialdigital data signal from the video source device to the shieldedconductors of said at least one dual shielded cable element.
 13. Thecable of claim 12, wherein the first circuit carrier further comprisesterminals for connecting at least one auxiliary signal from the videosource device to the shield of said at least one dual shielded cableelement.
 14. The cable of claim 11, further comprising a second circuitcarrier for connecting the raw cable to the video sink device.
 15. Thecable of claim 14, wherein the second circuit carrier comprises theboost device.
 16. The cable of claim 9, wherein said one or more highspeed differential digital data signals comprise Transition MinimizedDifferential Signaling (TMDS) signals; and said one or more auxiliarysignals comprise Consumer Electronics Control (CEC), Serial Clock (SCL),Hot Plug Detect (HPD), and +5V Power signals.
 17. The cable of claim 9,wherein: the shielded conductors of four dual shielded cable elementsextending between the video source device and the boost device; theshielded conductors of the four dual shielded cable elements are adaptedto carry respective four high speed differential digital data signals,which are Transition Minimized Differential Signaling (TMDS) signals;the shielded conductors of one other dual shielded cable element,extending between the video source device and the video sink device, areadapted to carry an auxiliary signal, which is a HDMI Ethernet and AudioReturn Channel (HEAC) differential signal; and the shields of the fourdual shielded cable elements and said one other dual shielded cableelement are adapted to carry auxiliary signals, which are ConsumerElectronics Control (CEC), Serial Clock (SCL), Serial Data (SDA),Digital Data Channel (DDC)/CEC Ground, and +5V Power signals.
 18. Thecable of described in claim 16, wherein the boost device comprises anequalizer and an amplifier for equalizing and boosting the TMDS signalsrespectively.
 19. The cable of claim 10, wherein: the shieldedconductors of four dual shielded cable elements extending between thevideo source device and the boost device; the shielded conductors of thefour dual shielded cable elements are adapted to carry respective fourhigh speed differential digital data signals, which are Main Line lanes;the shielded conductors of one other dual shielded cable element,extending between the video source device and the video sink device, areadapted to carry an auxiliary signal, which is an Auxiliary Channel (AUXCH) differential signal; and the shields of the four dual shielded cableelements and said one other dual shielded cable element are adapted tocarry auxiliary signals, which are CONFIG1, CONFIG2, Ground, Hot PlugDetect (HPD), and DisplayPort power (DP_PWR) signals.
 20. The cable ofclaim 19, wherein the boost device comprises an equalizer and anamplifier for equalizing and boosting the Main Line lanes respectively.21. The cable of claim 1, wherein an impedance of said at least one dualshielded cable element is lower than a nominal impedance of the cablespecified in the cable specification, the cable further comprising: afirst circuit carrier connecting the video source device to the rawcable, the first circuit carrier including two padding resistors, eachpadding resistor being in series with a respective shielded conductor ofsaid at least one dual shielded cable element; and a second circuitcarrier connecting the raw cable to the video sink device, the boostdevice being mounted on the second circuit carrier for terminating saidat least one dual shielded cable element, and for boosting the highspeed differential digital data signal.
 22. A method for transmittingone or more high speed differential digital data signals and a one ormore auxiliary signals from a video source device to a video sink deviceover a digital video cable having a raw cable and a boost device, themethod comprising: carrying at least one high speed differential digitaldata signal from the video sink device to a boost device in a pair ofshielded conductors of the raw cable; boosting the at least one highspeed differential digital data signal in the boost device to produce aboosted signal, and transmitting the boosted signal to the video sinkdevice; and carrying at least one auxiliary signal on a shield of thepair of the shielded conductors.
 23. The method of claim 22, furtherincluding equalizing the at least one high speed differential digitaldata signal in the boost device.
 24. The method of claim 22, wherein thetransmitting comprises transmitting over the digital video cable, whichis one of the following: a High-Definition Multimedia Interface (HDMI)cable; a DisplayPort cable.